Usually, on each of the paper sheets, such as the banknotes, checks, gift certificates or the like, the serial number (i.e., character information of a predetermined digit number including alphabetical letters and figures) is printed for identifying each paper sheet.
For instance, in financial institutions, one machine, which is adapted for character-identifying (or performing character identification for) the serial number of each banknote, registering each character-identified serial number at a database, and then managing the banknotes used in a certain transaction performed by using this machine, has been known in recent years (e.g., see JP2004-213559). In such a known machine, when some characters of a certain serial number are not identified, each part corresponding to such unidentified characters is rewritten and displayed by using an error letter (e.g., “?”). In this case, the user of this machine checks, visually, each actual banknote and then inputs, manually, each character corresponding to the error letter “?”. However, for this checking and input operation, it is necessary for the user to keep or prepare each actual banknote at hand. Therefore, such a manual input operation for each error letter tends to lay a heavy burden on the user.
In order to reduce such a heavy burden on the user, another machine, which is adapted for registering each unidentified character, as an unaccepted character, at the database, without the need for the manual input operation or the like, when there are some character (or characters) that cannot be identified, has been known (e.g., see WO2010/032335A1). In this case, however, if there is some unaccepted character even for only one digit position included in a certain serial number, or even if there is only one digit position that has no character information for the characters constituting together the serial number, such information on the serial number should be registered, as unclear information, at the database.
Namely, in such conventional paper sheet handling machines as described above, the manual input operation for each error character tends to lay the heavy burden on the user, and there is a risk that some serial number may be registered, as the unclear information, at the database.